Microsoft has taken the wraps off a new version of Windows and a new wearable 3D gadget it calls the HoloLens.

The company showed the new headset, which lets users view and interact with three-dimensional images, at an event where it also revealed new features coming to the company's flagship operating software.

Executives said Windows 10 is designed to embrace the way people use computers today, offering a familiar experience as they switch back and forth from personal computers to tablets, smartphones and other gadgets such as gaming consoles or even holographic projectors.

Microsoft is expanding Cortana to serve as a search engine and personal assistant, capable of answering questions and responding to commands such as "Play music" on desktop and laptop computers, as well as mobile devices.

And in a break from past practice, Microsoft announced that Windows 10 will be released later this year as a free upgrade for anyone owning a computer or gadget that's currently running Windows 8.1 or 7, the two previous versions of the software.

Microsoft is making a big bet that Windows 10 will help it regain ground the company has lost to the mobile computing boom.

Windows has long been the dominating operating software for desktop and laptop computers, but that business has suffered as more people have begun using smartphones and tablets.

Microsoft tried to reach those users by emphasizing touch-screen features in its last update, Windows 8, but many traditional PC users found it jarring and difficult to navigate.

Hoping to win back a larger audience, Microsoft is promising Windows 10 will provide a familiar experience to users on across devices, and a common platform for software developers to create apps that work on all of them.

"Windows 10 is built for a world in which there are going to be more devices on the planet than people," CEO Satya Nadella told reporters and industry analysts at Microsoft's headquarters.

He said Microsoft wants to "enable that seamless cross-over, across devices as you move around at home and at work."